HSC Survey Results

Scots Bay Survey # 1 Results from 05/05/2024

Survey Details

3 commercial purse seiners conducted this non-fishing survey on 05/05/2024 starting at 20:00:00, which was 2.32 hours before hide tide.

NA.

There was a plankton tow and replicate conducted and CTD cast by Lady Melissa.

No tags were applied during this survey.

Since no fish were caught, no samples were obtained for target strength estimation.

Tides Tables

Tide Schedule for Margaretsville NS, Station #315m Source: www.waterlevels.gc.ca

Acoustic Equipment

Each vessel was equipped with a Simrad ES38-18/200-18C combi (2-in-1) transducer prior to the survey that contains a 38kHz split beam and 200 kHz single beam transducer. Data was logged to the computer hard-drive for post-processing. All participating boats were calibrated on 38kHz before the survey.

Survey Results

Main Results

The results are subject to change as DFO will re-evaluate data editing, area estimation and apply a target strength.

Preliminary biomass prediction for Scots Bay using standardized parallel transects is 78,662mt.

Transect Details

Table 1: Transect Details
Vessel Transect # Date/Time Start Date/Time End Start Lon Start Lat End Lon End Lat id Y X Yend Xend Location Distance (km) Speed
BP T01 2024-05-05 03:00:00 2024-05-05 03:00:00 -65.234 45.136 -64.791 45.286 NA NA NA NA NA SB 38.65 Inf
BP T02 2024-05-05 03:00:00 2024-05-06 03:00:00 -64.809 45.301 -65.231 45.152 NA NA NA NA NA SB 37.16 0
LM T01 2024-05-05 03:00:00 2024-05-05 03:00:00 -65.234 45.090 -64.748 45.252 NA NA NA NA NA SB 42.42 Inf
LM T04 2024-05-06 03:00:00 2024-05-06 03:00:00 -64.764 45.264 -65.295 45.080 NA NA NA NA NA SB 46.80 Inf
LM T02 2024-05-05 03:00:00 2024-05-05 03:00:00 -64.734 45.255 -64.548 45.307 NA NA NA NA NA SB 15.79 Inf
LM T03 2024-05-05 03:00:00 2024-05-06 03:00:00 -64.550 45.329 -64.758 45.267 NA NA NA NA NA SB 17.78 0
MS T01 2024-05-05 03:00:00 2024-05-05 03:00:00 -65.226 45.166 -64.826 45.311 NA NA NA NA NA SB 36.68 Inf
MS T02 2024-05-05 03:00:00 2024-05-05 03:00:00 -64.835 45.317 -65.050 45.250 NA NA NA NA NA SB 18.96 Inf
MS T03 2024-05-05 03:00:00 2024-05-06 03:00:00 -65.050 45.264 -64.849 45.325 NA NA NA NA NA SB 17.60 0
MS T04 2024-05-06 03:00:00 2024-05-06 03:00:00 -64.869 45.333 -65.051 45.276 NA NA NA NA NA SB 16.07 Inf
MS T05 2024-05-06 03:00:00 2024-05-06 03:00:00 -65.050 45.290 -64.887 45.339 NA NA NA NA NA SB 14.41 Inf

Survey Summary

Table 2: Acoustic Survey Results
Vessel Transect No.  Target Strength (db/kg) Mean Sa (/m2) Biomass Density (kg/m2)
BP T02 -35.5 -38.181 0.539
MS T01 -35.5 -39.605 0.389
BP T01 -35.5 -46.556 0.078
MS T03 -35.5 -49.506 0.040
MS T04 -35.5 -50.570 0.031
MS T05 -35.5 -50.573 0.031
MS T02 -35.5 -51.521 0.025
LM T01 -35.5 -51.664 0.024
LM T04 -35.5 -52.192 0.021
LM T03 -35.5 -55.730 0.009
LM T02 -35.5 -61.778 0.002
Note:
Transects are listed from greatest to least backscatter.
Table 3: Survey Summary Table
Layer Target Strength Area (km2) Mean Sa Density (kg/m2) Biomass (tons) Percent Area Percent Biomass Standard Error (tons) Standard Error (%)
Main Box -35.5 387.3 -42.5968 0.2104 75,572.583 71.1 96.1 41,333.75 54.69
Northern Box -35.5 83.3 -50.4965 0.0317 2,636.303 15.3 3.4 252.73 9.59
Eastern Box -35.5 73.9 -57.6244 0.0059 453.113 13.6 0.6 263.36 58.12

Greatest Biomass Densities

A snip from the transect with the greatest biomass density (kg/m2)

A snip from the transect with the greatest biomass density (kg/m2)

The single point with the largest biomass density (kg/m2) was recorded by BP, at the following location:

The transect with the greatest average biomass density (kg/m2) was recorded by BP, at the following location:

Annual Summaries

Table 4: Annual Comparison Table
Current Year
Previous Year
Ground Survey Number Survey Date HSC Estimate HSC Turnover Adjusted Survey Date HSC Estimate HSC Turnover Adjusted DFO Estimate DFO Turnover Adjusted
Scots Bay 1 2024-05-05 78,662 NA 2023-05-22 40,856.000 40,856 0 0
Scots Bay 2 2024-05-20 29,842 17,255 2023-06-06 113,767.329 108,783 NA NA
Scots Bay 3 NA NA NA 2023-06-18 34,279.387 15,158 NA NA
Scots Bay 4 NA NA NA 2023-07-02 11,744.776 5,113 NA NA
Scots Bay 5 NA NA NA 2023-07-16 19,282.634 17,575 NA NA
Scots Bay 6 NA NA NA 2023-07-30 4,549.933 1,904 NA NA
Scots Bay 7 NA NA NA 2023-08-13 4,298.806 3,616 NA NA
Scots Bay 9 NA NA NA 2023-09-10 3,053.669 2,916 NA NA
Scots Bay 10 NA NA NA 2023-09-24 3,419.932 2,997 NA NA
Scots Bay 8 NA NA NA 2023-08-27 2,896.659 2,300 NA NA
Scots Bay 11 NA NA NA 2023-10-09 3,387.515 2,971 NA NA
Table 5: Annual Summary Table
Year Ground HSC Estimate HSC Turnover Adjusted DFO Estimate DFO Turnover Adjusted
2023 Scots Bay 241,536.6 204,189 NA NA
2024 Scots Bay 108,504.0 17,255 NA NA

Tagging, Plankton, and CTD Data

Tag Data

Plankton Data

Tow Summary Table

Tow 1
Tow 2
Base Details
Vessel Lady Melissa Lady Melissa
Set Number SB2024-01 SB2024-02
Ground SB SB
Date 05/05/2024 05/05/2024
Wind Direction (km/h) S S
Swell (m) 0.5 0.5
Air Temp (c) 9 9
Tow Details
Tow Start 18:58:00 19:17:00
Tow End 19:08:00 19:27:00
Start Lat 45.03600 45.06183
End Lat 45.04967 45.06783
Start Lon -65.25283 -65.21333
End Lon -65.22883 -65.17650
Avg Tow Depth (m) 5.635746 4.219848
Speed 7.8 7.8
Heading 50 91
Tide Direction with against
Other Data Collection
Flow Start 690652 742785
Flow End 742785 809001
No. Revolutions 52133 66216
Distance (m) 1400.970 1779.423
Volume 4401.148 5590.056
Secchi Disappear (m) 7 7
Secchi Reappear (m) 6 6

Tow Depth Profiles

Plankton tow depth profile #1

Plankton tow depth profile #1

Plankton tow depth profile #2

Plankton tow depth profile #2

The first tow is SB2024-01, which was with the tide and had an average depth of 5.6357465m. The second tow is SB2024-02, which was against the tide and had an average depth of 4.2198481m.

Captured plankton

Captured plankton from the surface tows

Captured plankton from the surface tows

CTD Data

CTD depth profiles for all 2024 Scots Bay surveys so far.

Sea surface temperatures

Annual average sea surface temperatures (SST) for Scots Bay.

Vessel Performance

Speed

Average vessel speed was Inf. This is above the 8 knot requirement; vessels are urged to slow down to prevent backscatter noise from interfering with the acoustic data.

Distance

No significant distance was cut from the planned lines; vessels covered the planned area well.